JPH08237684A - Television receiver - Google Patents

Abstract

(57) [Summary] [Object] It is an object of the present invention to provide a television receiving device in which crosstalk between YCs is small and the resolution is not deteriorated at the time of a moving image or a still image. A television receiver includes a motion detecting means for detecting a magnitude of motion from a received television signal, and a spatio-temporal filter in which a pass band in a horizontal frequency region changes according to a result of motion detection by the motion detecting means. And a demodulation means for demodulating the extracted chrominance signal and luminance signal, respectively, and a pass band in the horizontal frequency region of the spatio-temporal filter is output by the motion detection means. The passband is controlled to be narrower when the movement is smaller than that when the movement is small. According to the receiving apparatus of the present invention, crosstalk between YCs can be reduced and the resolution of a moving image or a still image can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for a luminance signal and a chrominance signal of a television signal, and more particularly, to reduce crosstalk between a luminance signal Y and a chrominance signal C and to provide a resolution for a moving image or a still image. The present invention relates to a television signal processing method or a television receiver suitable for YC multiplexing or YC separation with little decrease.

[0002]

2. Description of the Related Art In the current television system, a luminance signal Y
Is a composite signal in which the color signal C is superimposed on the color signal C. However, only the horizontal frequency is used to limit the crosstalk between Y and C, and in a moving image, the color between the Y and C signals such as cross color and cross luminance Image quality degradation due to crosstalk occurs. In order to improve this, it has been proposed that YC both perform "horizontal-vertical-time" three-dimensional band limitation on the transmitting side [Hirano et al., Three-dimensional signal of high-definition TV system having perfect communication capability]. Processing (No. 1), Proceedings of IEICE General Conference 1984, S14-11].

In order to facilitate the following description, the conventional proposal method will be briefly described. FIG. 1 shows a television signal of the conventional proposal system with a horizontal frequency μ, a vertical frequency ν,
It is a representation in three-dimensional frequency time-frequency f _t.
1 (a) is vertical frequency [nu, have the meanings indicated in the region of the time-frequency f _t, the color signal C of the current television system
Are inserted in the second quadrant and the fourth quadrant, as shown in FIG. That is, in the current television system, the first in FIG.
The quadrant and the third quadrant are vacant, and the high-frequency luminance signal Y _H ′ is inserted here as high-definition information in the above-mentioned conventional scheme.

FIG. 1 (b) shows a portion indicated by A in FIG. 1 (a) in a range of a horizontal frequency μ and a vertical frequency ν.

[0005] In the above conventional proposed method, C signal, Y _H 'signals and the low frequency luminance signal Y _L when multiple, three-dimensional frequency of "horizontal, vertical and time" in order to prevent crosstalk between the signal Limit the band by area. That is, as for the C signal, the hatched portion in FIG. 1 is set as a pass band, and Y _H ′ is set as a pass band in a region indicated by a dot. Then, Y _L is band-limited so that the passband portions of C and Y _H ′ are used as stopbands.

[0006] By doing so, image quality degradation due to crosstalk can be significantly reduced.

[0007] However, crosstalk is reduced by limiting the band, but there is a problem that the resolution of the band-limited portion is reduced. For example, the time frequency is 15H
The reduced luminance signal Y _L of z has a horizontal frequency of about 2.1 MHz or less, as shown in FIG.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a YC
It is an object of the present invention to provide a YC multiplex system or a television receiving apparatus in which crosstalk between images is small, and a decrease in resolution during a moving image or a still image is small.

[0009]

In order to achieve the above object, the present invention performs YC multiplexing so that the band limitation of the luminance signal Y on the image transmitting side is as small as possible.

[0010] Crosstalk occurs and band limitation is required for moving images. Therefore, in the present invention, a moving image and a still image are determined based on a signal from the imaging system, and the band of the luminance signal is limited only in the case of a moving image. In the conventional manner, to the Y signal and multiplexed there are high-frequency luminance signal Y _H 'in addition to the C signal. However, Y _H 'are in the case of video, not multiplexed since it is considered that the component is small. In the current NTSC system, only the C signal is multiplexed regardless of a still image and a moving image. Therefore, Y
May be limited only where crosstalk with the C component occurs.

Therefore, it is considered to reduce the crosstalk portion with the C component as much as possible. That is, in the case of a moving image, the C component is band-limited so as to have a narrower frequency band than in the case of a small motion. As a result, the Y band limitation is limited to a narrow area, and reduction in resolution during moving images is reduced. For the sake of simplicity, a case in which the horizontal frequency band is controlled will be described. In the case of a moving image, the C component is divided into a reduced frequency component C _L and a high frequency component C _H , and C _H is in the first and third quadrants of the “vertical-time” frequency region in which Y _H ′ was inserted. insert and frequency shift, so that the horizontal frequency included in the frequency of C _L. Alternatively, in consideration of the visual characteristics for a moving image, in the case of a moving image, the color signal may be band-limited to the low frequency component C _L and the remaining high frequency component C _H may not be multiplexed, that is, may not be transmitted. As a result, the crosstalk component of the horizontal frequency with Y is reduced, the band limitation of Y can be reduced, and the resolution of the moving image can be improved.

FIG. 2 shows an example of the frequency spectrum of the television signal in the case of a moving image according to the present invention. Figure 2
(A) shows in the "vertical-time" frequency domain, and (b) shows the portion (B) where the time frequency is 15 Hz in (a) in the "horizontal-vertical" frequency domain. It is a thing. In FIG. 2, the shaded area indicates the stop band of the Y-bandwidth spatio-temporal filter. As shown in FIG. (B), and multiplexed in a frequency band included in C _L to frequency shift a C _H, or zone results were not to transmit Y a C _H Conventional 2.
It was possible to widen from 1MHz to about 3.2MHz, and the resolution at the time of animation improves.

[0013] Figure 3, Figure 4 is a diagram showing a specific example of the frequency shift of the C _H of the present invention. In this example, C _H indicates the case of the high frequency component I _H of the color difference signal I. First, as shown in FIG. 4, from I (0 to 1.5 MHz) to I _H (0.5 to 1.5 MH)
z) is extracted. And the carrier frequency is 2.7MHz
Moreover sideband I _H '(3.2 in the signal by amplitude modulation of the I _H
~ 4.2 MHz) is extracted. At this time, I _H ′ becomes “vertical −
In order to be inserted in the first and third quadrants of the "time" region, the phase of the carrier frequency is inverted for each scan line and each field.

On the other hand, the low-frequency component I _L (0 to 0.5) of the color difference signal
MHz), Q _L (0~0.5MHz) is the color subcarrier (frequency about the same as the current television system (NTSC) 3.5
8 MHz). And, together with I _H ′,
The signal is multiplexed with the luminance signal Y and transmitted.

Since the signal format of the multiplex system of the present invention is the same as that of the current system, it can be received by the current receiver as it is. The newly added high-frequency luminance signal component Y _H ′ and high-frequency color signal component C _H are modulated by a signal whose phase is inverted between the fields and between the scanning lines as described above, and the energy is also increased. Because it is small, it does not interfere.

The receiving apparatus of the present invention comprises a motion detecting means for detecting the magnitude of motion from a received television signal, and a spatiotemporal space in which the pass band in the horizontal frequency region changes according to the motion detection result of the motion detecting means. It has a filter means for extracting a color signal and a luminance signal, each of which has a filter, and a demodulation means for demodulating the extracted color signal and luminance signal. The pass band in the horizontal frequency domain of the spatiotemporal filter is controlled by the output of the motion detecting means so that the pass band becomes narrower when the motion is larger than when the motion is smaller.

When the television signal according to the YC multiplex system of the present invention is received, the receiving apparatus of the present invention
I _H ′ is synchronously detected at the same frequency as that of the image transmitting side, and the lower band is taken to obtain the original I _H (0.5 to 1.5 MHz).
Play back z). Then, the original color difference signal (0 to 1.5 MHz) is obtained in combination with the separately demodulated I _L and Q _L.
However, the color difference signal I up to 1.5 MHz in still images
With the method that does not send the band-limited high-frequency components in the 0.5MHz in the case of video, the construction for reproducing the I _H during movie is not of course necessary. In both types, the receiver requires a pass band when the horizontal frequency of the spatio-temporal filter for detecting the motion of the image and extracting the color signal is large when the Y signal and the C signal are separated from the received signal. It is to make it narrower than when it is small. Thus, it is possible to prevent a decrease in the resolution of a luminance signal in a moving image in the receiving device.

When a television signal according to the current NTSC system is received, the receiving apparatus of the present invention reduces the pass band at the horizontal frequency of the spatio-temporal filter when extracting a color signal when the motion of an image is large. Thus, the influence of the cross color can be suppressed as much as possible, and conversely, when the movement is small, the resolution can be improved by widening the color signal. Also, when the current television signal is received by the receiving apparatus of the present invention, the color signal of the moving image has a band of 0 to 0.5 MHz, but the color signal band of the current home receiver is about this level. It is considered that there is no problem in view of the fact that there is almost no problem and the visual characteristics of the moving image.

[0019]

EXAMPLE An example of the present invention will be described below.

FIG. 5 is a diagram showing the structure of the image sending side in the embodiment of the present invention. From the luminance signal Y from an imaging system (not shown), a motion component is extracted by a spatiotemporal filter 1,
The signal is input to the determination circuit 2 to determine whether the image is a moving image or a still image, and a control signal 3 indicating either a moving image or a still image is obtained. Here, FIG. 6A shows an example of the configuration of the spatiotemporal filter 1 for extracting a motion component, and FIG. 6B shows the characteristics thereof. FIG. It is. The determination circuit 2 in FIG. 5 determines that a moving image is present when the output signal of the spatiotemporal filter 1 is at a level equal to or higher than a certain value.

From the Y signal, a high-pass luminance signal 5 (4.2 MHz to 7 MHz) is further extracted by a high-pass filter 4 and enters an amplitude modulator 6. And the amplitude modulator 6
Then, the amplitude is modulated by the carrier f _M1 (frequency 3.58 MHz), and the lower band is extracted by the low-pass filter 7. At this time, the phase of the carrier f _M1 is inverted for each scanning line and each field.

On the other hand, the high-frequency luminance signal is removed from the Y signal by the subtracter 8, and a low-frequency luminance signal 9 is obtained.

The color-difference signal I obtained from the image pickup system is converted by the reduction pass filter 10 into an I signal 12 (0 to
1.5 MHz) is extracted. Then, the narrow band I signal 13 is obtained by the other reduction pass filter 11. The subtractor 14 subtracts the wide-band I signal 12 and the narrow-band I signal 13 to obtain a high-frequency component 15 (0.5 MHz) of the I signal.
z˜1.5 MHz) is extracted and enters the amplitude modulator 16. In the amplitude modulator 16, the carrier fM ₂ (frequency 2.7M
Hz), and the upper band is extracted by the high-pass filter 17 to become a high-band I signal component 18 (3.2 MHz to 4.2 MHz) transmitted in the moving image mode. The phase of the carrier wave f _M2 is inverted for each field and each scanning line.

The Q signal obtained from the image pickup system is a signal 20 (0.5 MHz
z or less), and is quadrature-modulated by the quadrature modulator 21 together with the I signal component by the color subcarrier f _SC (3.58 MHz). At this time, the I signal component is switched by the switch 22 between the wideband signal 12 and the narrowband signal 13 according to the mode control signal 3.

Further, the output signal of the quadrature modulator 21 is added by an adder 23 to a high-frequency luminance signal component 18 'in the static mode and a high-frequency component 1 of the I signal in the moving image mode.
8 is added to the space-time filter 24. And
In the moving image mode, a signal whose band is limited by the spatio-temporal filter 24 is selected by the changeover switch 25, and in the stationary mode, a signal whose band is not limited is selected. The signal is added to the luminance signal by the adder 26 and transmitted. It becomes signal 27.

The reduced luminance signal 9 is band-limited by the changeover switch 29 and the subtractor 30 by the spatio-temporal filter 28 in the moving image mode, and is limited so as not to be band-limited in the stationary mode.

The mode information of the still image and the moving image is transmitted by inserting it into the first scanning line once in the field by the adder 31.

Here, the space-time filter 2 for band limitation
4 and 28 have the same configuration.
(A) and the characteristics are shown in (b) and (c) of FIG. Figure 7
Where F is a frame delay element, H is a scanning line delay element, and BPF
Is a band pass filter (3.2 MHz to 4.2 MHz).

FIG. 8 shows the configuration of the embodiment on the image receiving side in the present invention.

The still / moving mode information is extracted by the mode information extracting circuit 32 from the received NTSC signal. Then, the color signal and the high-frequency luminance signal component are extracted by the spatio-temporal filters 33 and 34 for a still image and a moving image. In the moving image mode, the signal of the spatiotemporal filter 34 is selected. Here, the configuration and characteristics of the spatiotemporal filter 33 for the stationary mode are shown in FIGS. 9A and 9B. In the figure, F is a frame delay element. Spatio-temporal filter for video mode 3
4 is the same as that shown in FIG.

The color signal and the signal 37 of the high-frequency luminance component are
The spatio-temporal filter 38 extracts the components of the first and third chapters in the “vertical-time” frequency domain, and demodulators 39 and 40.
, And are synchronously detected by the carriers f _M1 and f _M2 .
Here, the phases of f _M1 and f _M2 are inverted for each field and each scanning line. The signal from the demodulator 39 is supplied to a high-pass filter 41.
, The high-frequency luminance signal 42 is reproduced. Further, the signal from the demodulator 40 passes through the low-pass filter 43 and the high-pass component 44 (0.5 to 1.5 MHz) of the color difference signal I is reproduced.

The reduced luminance signal 45 is obtained by removing the signal 37 of the color component and the high-frequency luminance signal component from the received signal, and is added by the adder 46 to the reproduced high-frequency luminance signal 42. Note that it is not added for moving images. Also, it is not similarly added when the current television signal is being received.

On the other hand, the spatio-temporal filter 47
The components of the second and fourth quadrants of the "time" frequency domain are extracted,
The demodulator 48 performs synchronous detection with the color subcarrier f _SC . One of the outputs of the demodulator 48 is input to the low-pass filter 49, and the component 50 of the color difference signal I is obtained. In the moving image mode, the high-pass I component 44 is added to obtain the original I signal. When the image is a still image, nothing is added to the output of the low-pass filter 49 and the signal is output as an I signal. Similarly, when the current television signal is being received, nothing is added, and the output of the low-pass filter 49 is output as it is as the I signal. The other output of the demodulator 48 is input to the low-pass filter 50, and the Q signal is reproduced.

In the above-mentioned embodiment, the case of the color difference signal I as the high-pass color signal is shown, but the case of the Q signal may be used.
It goes without saying that a combination of I and Q may be used. Also,
At the time of moving images, the high-frequency color signal may not be sent.

Further, when switching between the still image mode and the moving image mode, there may be provided a period in which neither the high band luminance signal component nor the high band color signal component is once inserted.

[0036]

As described above, according to the receiving apparatus of the present invention, the crosstalk between YCs can be reduced and the resolution of moving images or still images can be reduced, and the effect is large.

[Brief description of drawings]

FIG. 1 (a) is a vertical-type television signal.
The figure shown in the time frequency domain. (B) is A- of FIG.
The figure which represented the cross section of A line in the horizontal-vertical frequency area.

2A is a diagram of a frequency spectrum of a television signal of the present invention, and FIG. 2B is a cross-sectional view taken along a line BB in FIG. 2A.

FIG. 3 is a frequency spectrum of a television signal of the present invention.

FIG. 4 is a diagram illustrating a frequency shift of a high-frequency color signal component according to the present invention.

FIG. 5 is a configuration diagram on an image transmission side in the embodiment of the present invention.

FIG. 6 is a configuration example of a spatiotemporal filter.

FIG. 7 is a configuration example of a spatiotemporal filter.

FIG. 8 is a configuration diagram on the image receiving side in the present embodiment.

FIG. 9 is a diagram showing the configuration and characteristics of a spatiotemporal filter for YC separation.

[Explanation of symbols]

1 ... spatio-temporal filter, 2 ... decision circuit, 3 ... mode information,
4: high-pass filter, 6, 16: amplitude modulator, 21:
Quadrature modulator, 7, 10, 11, 19: low-pass filter, 17: high-pass filter, 24, 28: space-time filter, 12: wide-band color difference signal, 13: narrow-band color difference signal, 3
2 ... mode information extracting circuit, 33 and 34 ... yCy _H 'space-time filter for separation, 36 ... mode information, 37 ... C-
Y _H 'signal, 45 ... reduced luminance signal, 38 and 47 ... space-time filter, 39,40,48 ... demodulator, 41 ... high-pass filter, 43,49,50 ... reduction filter.

Claims (3)

[Claims] 1. A television receiver for receiving a television signal in which a luminance signal and a color signal are frequency-multiplexed, a motion detecting means for detecting a magnitude of motion from the received television signal, and the received television. Filter means for extracting a color signal and a luminance signal respectively from the signal, the filter means having a spatio-temporal filter in which the pass band in the horizontal frequency region changes in response to the detection result of the motion of the motion detecting means; And a means for demodulating the color signal and the luminance signal extracted by the means. 2. The television receiver according to claim 1, wherein a pass band in the horizontal frequency region of the space-time filter is narrower when the movement is large as compared to when the movement is small. 3. The television receiver according to claim 1, wherein said filter means further comprises a space-time filter having said pass band as a stop band.